int_insertion_sort

while((j>0) && (p[j] <p[j-1])){
			swap(&p[j],&p[j-1]);
			j = j -1;

The thing to remember are 

1)The swap function takes in 2 integers hence we supply to it 2 addresses
2) The integers at the 2 addresses are those which do not hold with the invariant that the integer at the right is lesser than the integer at the left.